1. Field of the Invention
Embodiments of the present invention generally relate to equipment for performing semiconductor device fabrication, and more particularly, to an electrostatic chuck for supporting a semiconductor wafer during processing.
2. Description of the Related Art
Electrostatic chucks are widely used for providing support to substrates (also referred to herein as semiconductor wafers or wafers) within semiconductor processing equipment such as a plasma processing chamber. An electrostatic chuck generally holds a substrate in a stationary position during processing of the substrate, i.e., during material deposition or etching. Electrostatic chucks utilize capacitive and Johnsen-Rahbeck attractive forces for holding the substrate in position.
One type of electrostatic chuck includes a body and a fluid distribution element covered with a layer of a dielectric material thereby forming a support surface. The body is generally conductive such that the body forms an electrode of the electrostatic chuck. A substrate is placed onto the support surface. The fluid distribution element includes a plenum that carries the fluid multiple passages formed in the support surface of the electrostatic chuck for distributing a heat transfer fluid such as a gas between the support surface of the chuck and the backside of the substrate. Generally, the gas fills the interstitial area between the electrostatic chuck and the substrate, thus enhancing the rate and uniformity of heat transfer between electrostatic chuck and the substrate.
In plasma processing chambers, the electrostatic chuck is subjected to high power radio frequency (RF) fields and high density plasmas in the vicinity of the substrate. In such plasma processing chambers, it is possible to have the gas breakdown due to high electric field generation in the gas passages. The operation and service life of the electrostatic chuck is adversely affected by plasma formation in the gas passages. Such plasma may damage the substrate, the electrostatic chuck or both. Furthermore, plasma formation in a gas passage can lead to arcing that forms particulate contaminants in the chamber.
There exist various techniques for reducing the plasma formation in gas passages. One technique includes inserting a porous dielectric plug into the passage at the surface of the chuck. The porosity of the plug is selected to ensure a dimension of the pores inhibits plasma formation, yet allows the heat transfer fluid to reach the substrate support surface. While the porous material provides protection against plasma formation, fabrication of such electrostatic chucks is difficult, time consuming and costly.
Accordingly, there is a need for an improved electrostatic chuck that reduces plasma formation and arcing.